1. Technical Field
The present invention relates to engines and, more particularly, to an improved engine for aeronautical applications which includes a core power plant and two modules connected thereto, and four modules if supercharged, a propeller speed reduction unit and an accessory drive gearbox, and if supercharged a step-up gearbox to drive the blower and also a damper between the engine crank shaft and the step-up or overdriven gearbox which couples to the blower as a unit, a fluid-type vibration damping unit interposed between the accessory drive gearbox and the core power plant, a urethane compound damper interposed between the propeller speed reduction unit and the core power plant, and other unique features acting in concert to significantly improve performance and longevity.
2. Description of the Prior Art
Aircraft engines are subjected to extreme conditions yet must function without fail in order to prevent catastrophic loss of life. This is especially true in the case of single-engine aircraft which have no backup engine power should the engine fail. It is also necessary to provide large amounts of thrust from the engine and propeller unit in order to both permit controlled flight and sufficient speed for the aircraft to get where it is going in a reasonable amount of time. To solve these problems, recent aircraft have utilized turboprop or turbojet engines which have a relatively high thrust-to-weight ratio and are generally reliable. However, such engines have inherent deficiencies, particularly in terms of cost and fuel consumption. There is therefore a need for an aircraft engine which is not of the turboprop or turbojet design to avoid the deficiencies of those designs yet has the beneficial features of the designs.
An engine which fits these needs is the traditional internal combustion engine having a plurality of pistons and cylinders which provide the driving force for the drive shaft. However, in terms of thrust-to-weight ratio, piston engines have heretofore been at the lower end of the spectrum and thus are usable for only certain aeronautical applications. There is therefore a need for an piston-driven aircraft engine which is usable in a greater number of situations and can substitute for and even replace other types of aircraft engines currently being used.
Another problem encountered with propeller driven aircraft is that when they take off or turn in flight, their propeller shaft is placed under extremely high loads. Forces from these loads are partly absorbed by the propeller shaft and partly transferred to thrust and rotational bearings which support the propeller shaft. However, some of these forces are undesirably transferred to the gear train connecting the propeller shaft to the crankshaft, the crankshaft itself, and other engine parts, e.g., connecting rods, pistons, and crankshaft bearings and seals. Many of these components are not designed to accommodate such forces. Consequently, the effective life of these components is reduced and the servicing and replacement of these components must be done more frequently. Further, the failure of one of these components in flight or during take off may cause the plane to crash, possibly resulting in human injuries and deaths and significant property damage. There is therefore a need for a propeller speed reduction unit which will substantially eliminate many of the above-described problems.
Another issue which occurs with aircraft is the design and operation of the secondary power system. Secondary power systems of the type used in single engine aircraft present significant and unique challenges to designers. Such power systems are typically required to provide a highly reliable and virtually uninterrupted source of power to flight or mission critical accessories or subsystems on the aircraft despite exposure to extremes in temperature and altitude.
In the jargon of aircraft power systems, the term xe2x80x9cPrimary Power Systemxe2x80x9d is generally meant to include only the primary propulsion engine, and the term xe2x80x9cSecondary Power Systemxe2x80x9d is sometimes used in a broad sense to include all power consuming accessories, gearboxes, accessory drives, and power sources on the aircraft other than the propulsion engine. The term xe2x80x9cSecondary Power Systemxe2x80x9d is used herein in a somewhat narrower context intended to include only those accessories, gearboxes, accessory drives, and secondary power sources receiving rotating shaft power from the propulsion engine.
Virtually all large aircraft secondary power systems include some form of engine gearbox operably connected to receive rotating shaft power from the propulsion engine, and most are configured to provide multiple mechanical drive shafts for connection to the accessories. Engine gearboxes also typically include gear trains to convert engine RPM into the proper speed for the accessories driven by those drive shafts, with typical accessories including an electrical generator, hydraulic pumps, an air turbine starter for the propulsion engine, and engine driven fuel pumps. Such engine gearboxes tend to rob power from the propulsion engine, however, and thus they are not generally used with piston-driven engines due to the limited power output from the engine. As such engine gearboxes are generally preferred, however, there is a need for an engine accessory drive for use with piston-driven engines which utilizes such an engine gearbox.
Therefore, an object of the present invention is to provide an improved engine for aeronautical applications.
Another object of the present invention is to provide an improved engine for aeronautical applications which includes a core power plant, an accessory drive gearbox, a propeller speed reduction unit and a xe2x80x9cspiderxe2x80x9d unit which controls oil distribution.
Another object of the present invention is to provide an improved engine for aeronautical applications which includes a propeller speed reduction unit for translating the drive shaft output to the propeller in an efficient and reliable manner.
Another object of the present invention is to provide an improved engine for aeronautical applications which provides a greater power output than other engines of its size.
Another object of the present invention is to provide an improved engine for aeronautical applications which includes an oil delivery system which has an air/oil centrifugal separator to separate and remove air bubbles from the oil.
Finally, an object of the present invention is to provide an improved engine for aeronautical applications which is efficient in design and which is safe and durable in use.
The present invention provides an improved engine for aeronautical applications which includes a core engine block having a block valley and having a drive shaft rotatably mounted within the core engine block and a motive device for rotating the drive shaft, the motive device including two cylinder banks in a V-type configuration. A propeller speed reduction unit is connected to the drive shaft for transferring power from the drive shaft to a propeller mounted on the propeller speed reduction unit and an accessory drive gearbox is connected to the drive shaft for transferring power from the drive shaft to at least one accessory device connected to the accessory drive gearbox. The accessory drive gearbox includes an accessory drive crank gear connected to the drive shaft and a drive gear intermeshing with the crank gear for translating rotation of the crank gear to at least one accessory drive gear intermeshed therewith. At least two inter-module dampers are mounted in the engine, at least one of the inter-module dampers positioned between the core engine block and the accessory drive gearbox and at least one of the inter-module dampers positioned between the core engine block and the propeller speed reduction unit, each of the at least two inter-module dampers operative to dampen and isolate vibrations preventing destructive resonances from initiating. Finally, at least two coolant pumps are connected in fluid transmission connection to the core engine block, the at least two coolant pumps operative to circulate coolant fluid within the core engine block for cooling thereof, the at least two coolant pumps connected in redundant fluid connection whereby individual cylinder banks are cooled by a specific one of the at least two coolant pumps and, in the event of failure of one of the at least two coolant pumps, the remaining pump via a system of bypass and check valves, together with cross-feed lines, ensures continued coolant liquid flow from the remaining pumps to core engine block.
The improved engine of the present invention is specifically designed to solve the problems found in the aviation field. Specifically, the present invention provides an engine which has a relatively high thrust-to-weight ratio and is generally reliable while simultaneously being relatively inexpensive and miserly in fuel consumption. Furthermore, as the present invention provides both an accessory drive gearbox and a propeller speed reduction unit which are durable in construction and offer extended working lifetimes, repair costs are kept low while still supplying the needed functional characteristics of a desirable aircraft engine. Finally, the present invention provides a piston-driven aircraft engine which is powerful yet reliable and light-weight, a difficult feat to accomplish in the piston-driven engine field. The present invention thus provides a substantial improvement over those devices found in the prior art.